#region PDFsharp - A .NET library for processing PDF
//
// Authors:
//   Stefan Lange (mailto:Stefan.Lange@pdfsharp.com)
//
// Copyright (c) 2005-2009 empira Software GmbH, Cologne (Germany)
//
// http://www.pdfsharp.com
// http://sourceforge.net/projects/pdfsharp
//
// Permission is hereby granted, free of charge, to any person obtaining a
// copy of this software and associated documentation files (the "Software"),
// to deal in the Software without restriction, including without limitation
// the rights to use, copy, modify, merge, publish, distribute, sublicense,
// and/or sell copies of the Software, and to permit persons to whom the
// Software is furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included
// in all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
// THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER 
// DEALINGS IN THE SOFTWARE.
#endregion

using System;
using System.Diagnostics;
using PdfSharp.Internal;
using PdfSharp.Pdf.IO;
using PdfSharp.Pdf.Internal;

namespace PdfSharp.Pdf.Filters
{
  /// <summary>
  /// Reserved for future extension.
  /// </summary>
  public class FilterParms
  {
    // not yet used
  }

  /// <summary>
  /// Base class for all stream filters
  /// </summary>
  public abstract class Filter
  {
    /// <summary>
    /// When implemented in a derived class encodes the specified data.
    /// </summary>
    public abstract byte[] Encode(byte[] data);

    /// <summary>
    /// Encodes a raw string.
    /// </summary>
    public virtual byte[] Encode(string rawString)
    {
      byte[] bytes = PdfEncoders.RawEncoding.GetBytes(rawString);
      bytes = Encode(bytes);
      return bytes;
    }

    /// <summary>
    /// When implemented in a derived class decodes the specified data.
    /// </summary>
    public abstract byte[] Decode(byte[] data, FilterParms parms);

    /// <summary>
    /// Decodes the specified data.
    /// </summary>
    public byte[] Decode(byte[] data)
    {
      return Decode(data, null);
    }

    /// <summary>
    /// Decodes to a raw string.
    /// </summary>
    public virtual string DecodeToString(byte[] data, FilterParms parms)
    {
      byte[] bytes = Decode(data, parms);
      string text = PdfEncoders.RawEncoding.GetString(bytes, 0, bytes.Length);
      return text;
    }

    /// <summary>
    /// Decodes to a raw string.
    /// </summary>
    public string DecodeToString(byte[] data)
    {
      return DecodeToString(data, null);
    }

    /// <summary>
    /// Removes all white spaces from the data. The function assumes that the bytes are characters.
    /// </summary>
    protected byte[] RemoveWhiteSpace(byte[] data)
    {
      int count = data.Length;
      int j = 0;
      for (int i = 0; i < count; i++, j++)
      {
        switch (data[i])
        {
          case (byte)Chars.NUL:  // 0 Null
          case (byte)Chars.HT:   // 9 Tab
          case (byte)Chars.LF:   // 10 Line feed
          case (byte)Chars.FF:   // 12 Form feed
          case (byte)Chars.CR:   // 13 Carriage return
          case (byte)Chars.SP:   // 32 Space
            j--;
            break;

          default:
            if (i != j)
              data[j] = data[i];
            break;
        }
        if (j < count)
        {
          byte[] temp = data;
          data = new byte[j];
          for (int idx = 0; idx < j; idx++)
            data[idx] = temp[idx];
        }
      }
      return data;
    }
  }
}
